Commercial products such as low-E coatings used for solar energy management effectively block large amounts of infrared (IR) radiation but fail to block significant amounts of ultraviolet (UV) radiation. Meanwhile, coatings specifically designed to block UV radiation tend to be fairly transparent to IR radiation. Thus, there is a need in the art for a coating which is effective at blocking significant amounts of both IR and UV radiation.
A coating sol comprising zinc antimonate is known in the art, under the tradename Celnax. For example, see Nissan Chemical's website at www.snowtex.com/celnax.htm for the absorption spectrum of Celnax sol (zinc antimonate sol) which is mixed with a resin. The nanoparticles of the antimony double oxide absorb significant amounts of IR, while allowing a good portion of UV and significant amounts of visible radiation to transmit therethrough. For example, see U.S. Pat. No. 6,149,888, the disclosure of which is hereby incorporated herein by reference.
However, it would be desirable if such coatings could be designed so as to improve blockage of UV radiation.
In certain example embodiments of this invention, coatings are provided which block more UV radiation than those discussed above. In certain example embodiments of this invention, a composite oxide coating is provided that efficiently blocks both UV and IR radiation. Certain embodiments of this invention relate to a colloidal electro-conductive oxide solution having infrared (IR) and ultraviolet (UV) blocking characteristics. In certain example embodiments of this invention, a substantially transparent composite oxide coating is provided that includes a silica matrix, zinc antimonate, and a UV blocking material, thereby permitting the sol after application to block significant amounts of both IR and UV radiation. In certain example embodiments of this invention, a UV and IR blocking coating comprises each of cerium oxide and zinc antimonate in the form of nanoparticulate and silicon oxide (e.g., SiO2) formed from precursor materials such as silane(s). It has surprisingly been found that such coatings are effective at blocking both UV and IR radiation, and also are resistant to high temperatures as spectral response remains substantially unchanged in certain example instances after one or two hours of substantial heating (e.g., to about 400 or 450 degrees C.).
In certain example embodiments of this invention, the coating sol from which coatings are formed comprises from about 15 to 50% cerium oxide (more preferably from about 20 to 45%, and most preferably from about 30 to 40%), from about 30 to 70% zinc antimonate (more preferably from about 35 to 65%, and most preferably from about 40 to 55%), and from about 5 to 35% silicon oxide (more preferably from about 10 to 30%, and most preferably from about 12 to 25%). It has been found that these amounts of such materials in the coating sol provide a coating that is effective at blocking both UV and IR radiation, and is also resistant to high temperatures.
In certain example embodiments of this invention, there is provided a coating sol applied to a glass substrate to form a coating for blocking significant amounts of infrared (IR) and ultraviolet (UV) radiation, the coating comprising: silicon oxide: from about 5-35%; cerium oxide: from about 10-50%; and zinc antimonate: from about 30-70%. In certain example embodiments, the coated article has a transmission at 2300 nm of less than 10%. In certain example embodiments, the coated article has a transmission at 600 nm of at least about 60%, more preferably at least about 70%. In certain example embodiments, the coated article has an average transmission in the range of 300-380 nm of less than 25%, more preferably less than 15%, and most preferably less than 10%.